He said the New England Highway road section where the crash happened was ordinary.

"The road to me looked unremarkable," he said.

The crane in question was "for all intents and purposes" brand new, he said, having covered only about 400-500km.

"Everything seemed to be behaving normally" before the September 2013 crash, Dr Casey said.

The crane veered laterally, then went into the oncoming lane.

Dr Casey said the crane wheels left the road, and the machine went onto a verge, over an embankment, and came to rest in a field.

The crane's steering involved delivery of high pressure oil being delivered to cylinders.

"It was extremely easy to turn the wheel … you could do it with one finger if you wanted to."

Dr Casey found no oil leakage or damage in the crane cylinders when preparing an earlier report on the crash.

He said the crane involved gave little feedback to drivers.

Emergency services at the scene of a crash where a woman has been killed and three children seriously injured after a truck and a 4WD collided on the New England Hwy, just south of Toowoomba, Monday, September 16, 2013. Photo Kevin Farmer / The ChronicleKevin Farmer

The inquest was also examining whether speed limits for cranes should be altered, and how drivers ought to control wayward cranes.

"Speed never makes instability better," Dr Casey said.

The court also heard US manufacturer Terex was developing a crane with ABS brakes.